JP2004020981A - Display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To read out chart video data from a display memory having the chart video data stored therein in accordance with a prescribed display mode to display a video rotated at an arbitrary angle with respect to chart display. <P>SOLUTION: In a display memory, data which can be simultaneously written in and read from each prescribed two-dimensional area by operation of one cycle of memory access are stored, and there is provided a cache which reads or reads and rewrites and processes data of each two-dimensional square area being a prescribed unit when writing data in the display memory in a prescribed display mode or reading at a prescribed angle from the processing display memory. Data are read from the display memory by raster scan display scanning at an arbitrary angle, and a display video is rotated at an arbitrary angle and is directly displayed on a display device. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a device for displaying graphic data,
In particular, the present invention relates to a chart (chart) display device mounted on a moving body.
Hereinafter, a radar chart display device mounted on a ship will be described as an example.
[0002]
[Prior art]
A conventional chart display device will be described with reference to FIG.
[0003]
The CPU circuit 20 can take in its own heading (heading) data from the gyro interface circuit 17 and its own position data from the position information input circuit 18. As the position data, earth fixed latitude and longitude information is mainly used.
[0004]
The CPU circuit 20 reads a chart data source of the designated center position and scale from the chart database 19, and writes the data into the graphic frame memory 22 via the graphic control circuit 21. There is also a method of directly writing to the graphic frame memory 22 without passing through the graphic control circuit 21.
[0005]
The graphic frame memory 22 is read by display scanning, converted into a display video signal by a D / A conversion circuit 23, and displayed on a display 24.
[0006]
Generally, maps including marine charts are often displayed with the north directly above (north-up display, hereinafter referred to as NUP), but when the present display device is mounted on a mobile object, its own course is directly above the display. A fixed head-up display (hereinafter, HUP) or a course-up display (hereinafter, CUP) in which a set course is fixed just above the display are often used.
[0007]
The direction display has the above three modes.
[0008]
In the HUP, the top of the display screen coincides with the bow of the ship. Therefore, the display is the same as that observed by the observer from the bridge of the ship. That is, the fixed target and the like are displayed as if the own ship turned in the direction opposite to the turning direction.
[0009]
In NUP, the top of the display screen always points north. That is, the position of the fixed target such as an island on the screen displayed is fixed irrespective of the turn of the ship.
[0010]
In the CUP, the course immediately above the display screen is the course at the moment when the azimuth is fixed by the reset switch or the like of the CUP. Therefore, the moment when the bearing is fixed is the same as the display of the HUP, but when the ship turns, the effect becomes the same as the display of the NUP.
[0011]
In these three direction display modes, it can be said that the fixed target is fixed to the display screen for CUP and NUP, and the fixed target is displayed at a different position in accordance with the turn of the ship in HUP.
[0012]
Apart from these direction display modes, when the ship moves, the motion display mode is set to relative motion display depending on whether the position of the ship is fixed or displayed or the display of the position of the ship is moved and displayed. Mode (hereinafter, RM) and true motion display mode (hereinafter, TM).
[0013]
RM is a method in which the own ship display position (the center of coordinate transformation) is fixed and displayed. With the movement of the own ship, the fixed target relatively moves in the opposite direction to the movement of the own ship and is displayed. It is a method that In this RM, an image similar to that of an observer looking around the scenery around himself on a bridge is displayed.
[0014]
TM is a system in which the own ship display position is moved and displayed according to the movement (distance, direction) of the own ship, and the fixed target is displayed fixed at the display position. In the TM, the ship moves and is displayed on the chart according to the direction and distance in which the ship has moved.
[0015]
Therefore, as a display method for a ship, a combination of the HUP, NUP, and CUP in the direction display mode and the RM and TM in the motion display mode includes, for example, RM-HUP (head-up display mode of relative motion), TM The display mode is determined, such as -NUP (true motion north-up display mode).
[0016]
[Problems to be solved by the invention]
By the way, when the chart display is displayed by the HUP described above, and when the course of the own ship is changed, it is necessary to rewrite all the contents of the graphic frame memory so that the top right of the screen matches the course at that time. is there.
[0017]
Rewriting the graphic frame memory requires a two-step process of reading chart data from the chart database and writing display data to the graphic frame memory. If the chart display has a high resolution of XGA or SXGA, a high-speed CPU is required. It takes several seconds even when using a graphic control circuit.
[0018]
If it takes a few seconds from the change of course to the end of rewriting the display data, and in the case of a moving object whose course changes every moment, the rewriting is completed although the top of the chart display instantaneously matches the course of the ship. In the meantime, there will be no match, and it cannot be a true HUP.
[0019]
Further, since the chart display direction flies discontinuously in each rewrite cycle, the visibility is reduced.
[0020]
The present invention has been made in view of such circumstances, and a main purpose is to display a chart in a correct direction even in a situation where the movement of the own ship cannot be ignored or a case where the course of the own ship is constantly changed (turning). In addition to enabling the display to rotate, the display can be smoothly rotated according to the turn of the ship.
[0021]
[Means for Solving the Problems]
2. The display method according to claim 1, wherein in one cycle of memory access, data is simultaneously written and read out in a predetermined two-dimensional rectangular area in a predetermined two-dimensional rectangular area, and the display data is stored in a predetermined display mode. Raster scan is performed at a specified center position and angle from a display memory, data is read out for each of the predetermined two-dimensional square areas, and processed by a cache, thereby displaying an image rotated at a specified display angle. And
[0022]
3. The display device according to claim 2, wherein in one operation of memory access, data can be simultaneously written and read for each predetermined two-dimensional area, and display memory means for storing display data in a predetermined display mode; A first cache unit for reading display data for each of the predetermined two-dimensional square regions from a unit; and a raster scan at a specified angle from the display memory unit for reading data for each of the square regions. Second cache means for processing data along the line;
Display means for receiving and displaying the data from the second cache means,
An image obtained by rotating the display data stored in the display memory means by the specified angle is displayed.
[0023]
According to the present invention, a display memory for simultaneously writing data in a predetermined two-dimensional area and storing readable chart data and writing chart data to the memory in a predetermined display mode in one cycle of memory access operation, and When the chart data is read from this memory at a predetermined angle, a cache is provided for reading or reading and rewriting for each two-dimensional rectangular area of a predetermined unit, thereby performing raster scan display scanning at an arbitrary angle from the display memory. It is possible to read out, rotate the display image by an arbitrary angle, and directly display it on the display. Of course, the bow direction can always be fixed in a fixed direction, and the displayed image can be smoothly rotated according to the turning of the ship.
[0024]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0025]
FIG. 1 is a diagram showing an overall configuration of a marine chart display device according to an embodiment of the present invention, FIG. 2 is a configuration diagram of a display memory, and FIG. 3 explains a read operation from the display memory. FIG.
[0026]
In FIG. 1, a data write cache 6, a display address generation circuit 7, a memory address conversion circuit 8, a memory address conversion circuit 9, a memory control circuit 10, a display data cache 11, and a display data buffer 12 are provided. The memory 13 is significantly different in memory structure from the conventional graphic frame memory 22. The same reference numerals as those shown in FIG. 4 indicate the same components.
[0027]
As shown in FIG. 2A, the display memory 13 has N × M dots in the horizontal direction and M dots in the vertical direction, and has a total storage capacity of N × M dots. In one unit to be accessed, k = 8 and 64 dots of a two-dimensional rectangular area of 8 dots × 8 dots are arranged.
In the case of a memory such as an SDRAM capable of synchronous burst transfer, all dots in a predetermined two-dimensional rectangular area can be accessed in units of one burst.
The two-dimensional rectangular area has data of dots D0 to D63, as shown in FIG. Therefore, when each of the two-dimensional rectangular areas A0 to AN / K-1 to An... Is designated from the display memory 13, the 64-dot data included in the rectangular areas is read out at one time, or Written. The two-dimensional square area may be a square area such as 4 × 4 dots, 2 × 2 dots, etc. other than 8 × 8 dots, and may be not only a square area but also a rectangular area.
[0028]
As the data write cache 6, a memory element whose operation speed is remarkably faster than that of the display memory 13, for example, a register, a buffer, an SRAM (static RAM), or the like is used. Data of a predetermined two-dimensional rectangular area of the display memory 13 corresponding to the address specified by the CPU circuit 20 is read out to the processing data cache 6 via the memory control circuit 10. The data of the two-dimensional rectangular area is changed from the CPU circuit 20 to the predetermined data of the display memory 13 via the memory control circuit 10 after the content of the dot corresponding to the target address is changed to the predetermined data. That is, it is rewritten to the read address. The memory address conversion circuit 8 converts a write address from the CPU circuit into addresses of the respective two-dimensional rectangular areas A0 to AN / K-1 to An... Of the display memory 13. It is provided to the display memory 13 via the control circuit 10.
[0029]
The display address generation circuit 7 receives the display center position data and the display angle data from the CPU circuit 20, generates an address at that time, and supplies it to the memory address conversion circuit 9. The memory address conversion circuit 9 converts the display address in the display address generation circuit 7 into the addresses of the two-dimensional rectangular areas A0 to AN / K-1 to An... Of the display memory 13. The address is given to the display memory 13 via the memory control circuit 10. The display center data is indicated by a black dot in the center of FIG. 3A, and the display angle data is a raster scan direction indicated by a solid arrow in FIG.
[0030]
In FIG. 3A, a small square in the memory area of the display memory 13 of N × M dots is a display area for raster scanning. The display area is rotated around the display center position (black point) in accordance with the display angle data, and the data in the display area is displayed on the designated direction at the top. Therefore, the memory area of the display memory 13 has such a size that at least the display area can rotate at an arbitrary angle. For example, in the case of a general XGA screen, for example, 1024 × 768 dots, and in this case, the memory area of the display memory 13 is set to 2048 × 2048.
[0031]
Like the data write cache 6, the display data cache 11 uses a memory element whose operation speed is remarkably faster than that of the display memory 13, such as a register, a buffer, and an SRAM (static RAM). Data of a predetermined two-dimensional rectangular area of the display memory 13 is read into the display data cache 11 via the memory control circuit 10. Of the read data of the two-dimensional rectangular area, data along the display angle at that time is read and displayed on the display 24 via the display data buffer 12.
[0032]
In the present embodiment, an operation will be described in which chart data is written to the display memory 13 in the NUP display mode, and a chart image is rotated and displayed at a specified display angle at each raster scan display cycle.
[0033]
The operation of writing the chart data to the display memory 13 is performed at the designated scale by matching the center position of the designated memory with the latitude and longitude of the chart, as in the conventional chart display device.
[0034]
The write address output from the CPU circuit 20 is supplied to the memory address conversion circuit 8. The memory address conversion circuit 8 converts the supplied write address into a real memory address of the display memory 13 (that is, “A0 to AN / K-1 to An...” Described in the paragraph “0029”) and performs memory control. The data is supplied to the display memory 13 via the circuit 10.
[0035]
From the display memory 13, rectangular area data corresponding to the specified specific real memory address is simultaneously transferred to the data write cache 6.
[0036]
The write address from the CPU circuit 20 is supplied to the data write cache 6, and the dot data corresponding to the write data from the CPU circuit 20 in the transferred and stored rectangular area data is rewritten.
Since the chart drawing is performed continuously on adjacent dots, the reading operation of the data write cache 6 is performed a plurality of times by reading the rectangular area data once, and the frequency of accessing the display memory 13 can be reduced.
[0037]
When the write address moves and the data in the data write cache 6 has no data corresponding to the write address, the data in the data write cache 6 is written back to the display memory 13 and then the next corresponding write is performed. The rectangular area data in the display memory 13 corresponding to the address is read into the data write cache 6, and the chart data write operation is performed.
[0038]
The memory control circuit 10 arbitrates so that the access to the display memory 13 by the processing operation and the access to the display memory 13 by the display operation are not performed at the same time, so that both accesses to one display memory 13 can be performed. I do.
[0039]
Next, an operation of rotating and displaying the chart written in the display memory 13 by an arbitrarily designated angle will be described. In the following description, it is assumed that HUP display is performed, but it is of course possible to display in another display mode.
[0040]
First, display center position data and display angle data are set in the display address generation circuit 7 from the CPU circuit 20. This display center position data indicates the own ship position. Since the display memory 13 is drawn in NUP, the own ship position changes with the movement of the own ship. In a general usage, the screen is displayed so that the own ship position is located at the center position of the screen. Therefore, the display memory 13 of the NUP is displayed so that the center of the screen is located at the own ship position at that time. To update the display center position data. Also, in order for the bow direction to be fixed at the top of the screen, it is possible to calculate the angle at which the display scan should be set from the true heading data of the bow, and the display inclination is output as display angle data for each display scan. Is done.
[0041]
In the scanning operation, as shown in FIG. 3 (a), raster data is scanned in parallel with one side of video data within a small square centered on a black point so that one side is upward.
[0042]
The display address generation circuit 7 sequentially generates display addresses to be read out in accordance with raster scan scanning based on the set display center position data and display angle data. The display address is an identification value of the corresponding row and column of each dot on the plane on which the chart video is drawn, like the write address, and this value changes linearly in the row direction and the column direction. This display address is calculated according to parallel lines at regular intervals according to the scan density of the raster scan.
[0043]
This display address is converted into real memory addresses A0 to AN / K-1 to An... Of the display memory 13. That is, the real memory address for the display address is calculated along the scan line to be raster-scanned, and when the new real memory address is reached, the real memory address is obtained as a converted value.
[0044]
Since the display readout of the raster scan is a linear scan, display positions subsequent to an arbitrary display point can be easily predicted. Actually, in the read scan, the display position is sequentially operated at a predetermined cycle and an increment value. Therefore, at which point which data is read is determined in advance by the scan control.
[0045]
From the display memory 13, the rectangular area data corresponding to the real memory address (for example, An) obtained as the converted value is transferred to the display data cache 11.
[0046]
Since the raster scan is performed linearly, by placing the rectangular area data on the display data cache 11, a plurality of read operations are performed in one memory read, thereby reducing the frequency of access to the display memory 13. it can. Referring to FIG. 3B, data of 64 dots D0 to D63 included in the square area of the real memory address An is transferred to the display data cache 11 by one access to the display memory 13. The 64-dot data transferred to the display data cache 11 is sequentially read out at predetermined intervals along a readout direction line (that is, a raster scan direction) according to a display address, and display data is output a plurality of times from the rectangular area. Is done. In this example, data of 6 dots is output as display data.
[0047]
Here, the reason why high-speed scanning becomes possible will be specifically described. When the display data is read directly from the display memory 13, a three-step procedure of setting an address, waiting until the memory can output data, and holding output data is required, and this read operation is usually required for each dot. It is not possible in time to perform at the display scanning frequency that is assumed. For example, in the case of an XGA screen used for a normal personal computer screen or the like, the display period allowed per dot is about 13 nS, while even a high-speed display memory (eg, SDRAM) requires about 20 to 30 nS per memory access cycle. Since it is necessary, the required image data cannot be normally read directly from the memory. Although an SRAM has a high memory speed, its capacity is small due to a complicated circuit configuration per cell, and thus cannot be used as a display memory.
[0048]
On the other hand, in the present invention, by reading the data of the rectangular area (8 × 8 dots) collectively and transferring it to the display data cache 11, the reading of each dot data in the display scan is not a memory access, but a cache access. Register access is performed, and output can be performed in a few nS even with an IC using a normal CMOS process. As a result, the present invention can support high-speed raster scan scanning at a low memory access speed.
[0049]
Next, when the display address is updated and there is no display address data corresponding to the data in the display data cache 11, the rectangular area data in the memory control circuit 10 corresponding to the next corresponding display address is replaced with the display data. The data is read into the cache 11 and a raster scan display operation is performed.
[0050]
The number of readings from the rectangular area transferred into the display data cache 11 differs depending on the display location, and the contents of the display data cache 11 may need to be updated by at least one reading. If the display data is output directly from the display data cache 11 to the D / A conversion circuit 23 and the display 24, the display data may be interrupted. Therefore, the display data buffer 12 is provided, and the reading from the display data cache 11 is performed more than the display. This is performed several dots ahead, and the buffer size is determined so that the display data always remains in the display data buffer 12. As a result, the display data is output to the D / A conversion circuit 23 without interruption.
[0051]
In this embodiment, since the screen center position and the display angle are set for each screen display of raster scan scanning (about 17 mS), the chart image rotates and moves for each screen display of raster scan scanning. Therefore, with the heading fixed at the upper part of the screen, it is possible to follow the movement of the ship in real time and display a chart image that smoothly rotates and moves without flicker.
[0052]
In this way, the chart image that follows the movement of the ship in real time is displayed. Therefore, compared to the conventional HUP display mode in which the image is obtained only for each scan, the buoy is operated, for example, the bow is inserted in the bow direction. When maneuvering, etc. becomes easier.
[0053]
In the above embodiment, the chart data is written to the display memory 13 in the NUP mode. However, the present invention is not limited to this mode. For example, the chart data may be written to the display memory 13 in the CUP mode. .
In this way, the contents of the display memory drawn in NUP or CUP can be displayed in the HUP mode, and even in a situation where the movement of the ship cannot be ignored or a case where the course of the ship is constantly changed (turning), the chart can be displayed. It can be displayed correctly.
This makes it possible to easily recognize the relative positional relationship between the user and the target indicated in the chart.
[0054]
【The invention's effect】
In the display device of the present invention, the display image can be rotated to an arbitrary angle and necessary data can be directly displayed from the display memory by raster scan display scanning, so that the display image is smoothly rotated according to the turn of the ship. It becomes possible.
[0055]
In this way, the contents of the display memory drawn in NUP or CUP can be displayed in the HUP mode, and even in a situation where the movement of the ship cannot be ignored or a case where the course of the ship is constantly changed (turned), the surrounding situation is changed. Can be displayed correctly. That is, the fixed target indicated in the chart can be displayed in the correct direction.
This makes it possible to easily recognize the relative positional relationship between the user and the fixed target displayed in the chart. As a result, obstacles can be reliably found during the navigation of a ship or the like, greatly contributing to safe navigation assistance, and can be said to be effective display means.
[Brief description of the drawings]
FIG. 1 is an overall configuration diagram of a marine chart display device of the present invention. FIG. 2 is a configuration diagram of a display memory of the present invention. FIG. 3 is an explanatory diagram of a display memory reading direction of the present invention. FIG. 5 is an explanatory diagram of a conventional display memory readout direction. FIG. 6 is a conventional display memory configuration diagram.
Reference Signs List 6 Data write cache 7 Display address generation circuit 8 Memory address conversion circuit 9 Memory address conversion circuit 10 Memory control circuit 11 Display data cache 12 Display data buffer 13 Display memory 17 Gyro interface circuit 18 Position information input circuit 19 Chart database 20 CPU circuit 21 Graphic control circuit 22 Graphic frame memory 23 D / A conversion circuit 24 Display

Claims (2)

In one cycle of memory access operation, data is simultaneously written for each predetermined two-dimensional rectangular area, predetermined display data is stored in a predetermined display mode in a readable display memory, and
From the display memory, by raster-scanning at a specified center position and angle, reading data for each square area, and processing the data in a cache,
A display method characterized by displaying an image rotated at a specified display angle at a specified center position. Display memory means for simultaneously writing and reading data for each predetermined two-dimensional area in one cycle of memory access, and for storing predetermined display data;
First cache means for reading display data for each predetermined two-dimensional rectangular area;
A second cache unit for performing a raster scan from the display memory unit at a designated center position and angle, reading data for each of the predetermined two-dimensional rectangular regions, and processing data along a line of the raster scan;
Display means for receiving and displaying the data from the second cache means, and displaying an image obtained by rotating the display data stored in the display memory means at the specified center position and angle. Display device.

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